Bacteria Outline

Bacteria - Oldest, structurally simplest, most abundant forms of life - Only organism with prokaryotic cellular organization - The only members of the kingdom Monera (4800 different kinds) - Characteristics change depending on growth conditions - Maintenance of life depends on them - play vital role of productivity and as decomposers - Capable of fixing atmospheric N for use by other organisms - Used in production and fermentation of various food and as antibiotics and is being tested for insect control - Prokaryotes vs. Eukaryotes - Multi-cellularity - All bacteria fundamentally single celled - Sometimes cells adhere within a matrix to form filaments - Activities of bacterial colonies less integrated and coordinated than in multicellular eukaryotes Eukaryotes Bacteria Cell Size 10x size of bacteria 1 micrometer (çm) diameter Chromosomes Membrane bound nucleus w/ chromosomes w/ nucleic acid & proteins No nucleus/chromosomes w/ DNA DNA contained in cytoplasm Cell Division and Genetic Remcombination Mitosis involving microtubules Sexual reproduction - meiosis/syngamy Binary fusion Lack of sexual reproduction - no equal participation Internal Compartementalization Respirational enzymes packed into mitochondria Corresponding enzymes bound to cell membranes Cytoplasm - no internal compartments/organelles (except ribosomes) No cytoskeleton Flagella Complex 9+2 structure of microtubules (whip-like motion) Simple w/ a single fiber protein flagellin Spins like a propellar Autotrophic Diversity Enzymes for photosyn. Packed in membrane-bound organelles (plastids) Only 1 type of photo. - release of O2 Enzymes bound to cell membrane Several patterns of aerobic/anaerobic photo. w/ formation of S, O, sulfate Chemosynthesis - process where certain bacteria obtain energy from oxidation of inorganic compounds and obtain C from CO2 - Bacterial Structure - Lypopolysaccharide - polysaccharide chain with lipids attached - Molecules of it deposited over layer of gram positive - forming outer membrane - Makes gram negative bacteria resistant to many antibiotics to which gram positive bacteria are susceptible - Capsule - gelatinous layer surrounding cell - Bacilli - straight, rod-shaped bacteria - Cocci - spherical bacteria - Spirilla - spirally coiled bacteria - Spores - single-celled bodies that grow into new bacterial individuals - Some bacteria change into stalked structures, grow long, branched filaments or form erect structures that release spores - Bacterial cells have simple structures - 2 kinds of cell walls - gram negative/positive - Cytoplasm of a bacterium contain no internal compartments/organelles & is bound by a membrane encased w/i a cell wall composed of 1/more polysaccharides - Pili - other kinds of hairlike outgrowths that occur on some bacteria cells - shorter than flagella - Help bacterial cells to attach to appropriate substrates - Endoscopes - resistant to environmental stress; may germinate & form new bacterial individuals after decades/centuries - Bacterial Variation - 2 processes lend variability to bacterial reproduction - Mutation - Because of the short generation time of bacteria whose populations often double in a few min., mutation plays important role in generating genetic diversity - Genetic Recombination - Transfer of genes from one cell to another as portions of viruses, plasmids, other DNA fragments *Intestinal bacterium: typhoid, dysentry, other diseases - Bacterial Ecology and Metabolic Diversity - Bacteria most abundant organisms in most environments - Obligate anaerobes - organisms cannot grow in presence of O2 - Facultative anaerobes - organisms that function as anaerobes/aerobes - Aerobes - organisms that require O2 - Autotrophic bacteria - Heterotrophs - get energy from organic material formed by other organisms (most bacteria) - Autotrophs - obtain energy from nonorganic sources - Photosynthetic bacteria - contain chlorophyll but not held in plastids *Cyanobacteria, green/purple sulfur bacteria, purple nonsulfur bacteria - Different colors caused by photosynthetic pigments - Chemoautotrophic bacteria - derive energy from the oxidation of inorganic molecules (N, S, Fe compounds, gaseous H) - Heterotrophic bacteria - Saprobes - bacteria that obtain nourishment form dead organic material - Autotrophic bacteria, capable of making their own food, obtain energy from light or the oxidation of inorganic molecules - Heterotrophic bacteria obtain energy from breaking down organic compounds made by other organisms - By-products of bacterial metabolism - Antibiotics - valuable - Botulism - food poisoning - Salmonella - gastrointestinal disease - N-fixing bacteria - N fixation - carried out by nodule-forming bacteria - Bacteria releases fixed N (when they break down proteins) - N cycle carried out exclusively by bacteria - Bacteria as plant pathogens - Most plant diseases caused by bacteria - Most bacteria that cause plant diseases are from a group of rod-shaped bacteria called pseudomonads * Citrus canker (Florida) - destroy citrus seedlings - Bacteria as human pathogens - Cholera, leprosy, tetanus, bacterial pneumonia, whooping cough, diptheria - Many diseases dispersed in food/water - Legionnaires’s Disease - Severe pneumonia - fatal in 15-20% of victims if untreated - Caused by legionella - small, flagellated, rod-shaped, gram/-, bacteria w/ pointed ends - Common in water - Attacks monocytes (type of white blood cell) - Destroyed with erythromycin treatment - Sexually Transmitted Diseases - Gonorrhea, syphilis - controlled w/ antibiotics (syphilis - penicillin) - Infections caused by Chlamydia trachomatis (bacteria) - Painful symptoms - causes sterility - Controlled w/ antibiotic tetracycline - Causes arthritis in young people - Dental Caries (decay) - Causes cavities in dental plaque (film on teeth) - Plaque consists of bacteria cells surrounded by polysaccharide matrix - Caused by diets high in sugar - Prevented w/ antibiotics - Bacterial Diversity - Archaebacteria - distinctive membranes, unusual cell walls, unique metabolic cofactors - Eubacteria - kingdom Archaebacteria belongs in - Methanogenic - prominent Archaebacteria - Produce methane from CO2 & H to obtain energy - Source of marsh gas - Reduce S to form hydrogen sulfide - Archaebacteria ancient group of prokaryotes that are different from eubacteria - seem to be direct ancestors of eukaryotes - Omnibacteria - rigid, rod-shaped, heterotrophic, gram/+ - Vibrios - comma-shaped that have single terminal flagellum - Obligate parasites - organisms that can live only as parasites - Rickettsias - bacteria causing Rocky Mountain spotted fever - Cyanobacteria - photosynthetic bacteria - bring about increase of free O2 in the atmosphere (crucial for eukaryotic evolution) - Produce accumulation of limestone deposits (stromatolites) - Phycobilins - accessory pigments that are blue & red & water soluble - Only in cyanobacteria, red algae, & cryptomonads - Mucilaginous sheath that can be different colors (blooms in H2O) - Fix atmospheric N in cells called heterocysts (especially important in rice fields) - Chloroxybacteria - photosynthetic bacteria - Fixes N - Biochemical characteristics give rise to chloroplasts of green algae - Mycoplasmas - Aphragmabacteria (phylum name) - Cause diseases in mammals & birds *Premature labor in women *Pneumonia - Treated with antibiotics - Spiroplasmas - cause plant diseases *Aster yellow - Both (spiro-/myco- plasmas) lack cell walls & cells bounded by 3-layered lipid membrane - Resistant to antibiotics & penicillin working to inhibit cell growth - Spirochaetes - long spirilla where flagella are inserted beneath outer lipoprotein membrane of gram/- outer cell wall - Agents of syphilis & yaws (disfiguring eye disease) *Lyme disease (inflammatory ailment)- treated w/ penicillin/tetracycline -Pseudomonads - straight/curved gram/- rods w/ 1/more flagella at one ent - Soil/water - break down organic compounds (autotrophic) - Plant pathogens - infections to people who eat the plants -Actinomycetes - produce spores by division of terminal, erect branches into chains of small segments - N fixing molecules formed at roots of flowering plants - Dental plaque, leprosy, tuberculosis - Ivermectin - antiparasitic agent, tetracycline, etc. made from actinomycetes -Myxobacteria - gliding bacteria - unicellular rods - Cells embedded in slimy polysaccharides they excrete - Occur in soils - aerobes - N Fixing Aerobic Bacteria - gram/- and flagellated - Soil/water - converts N to a form which can be used by other organisms and itself - Fermenting bacteria - obligate anaerobe - N fixing -Chemoautotrophic bacteria - Chemoautotrophy - metabolism that depends on chemical sources of energy like methane, ammonia, hydrogen sulfide - Do not require sunlight - Use N compounds to gain energy (Nitrosomonas) - Oxidize inorganic S or Fe compounds to gain energy - Use methane/methanol